Other networks will only be permitted to air a single 30-second clip of the debate on their stations and websites in the hours between 11 p.m. Wednesday and 5 a.m. Thursday.

What's that mean? Well, for one it means Fox News, MSNBC and the rest will have to choose wisely. Secondly, it means if Hillary Clinton or Barack Obama wants to drop a bomb, he or she will have to boil it down into less than 30 seconds if they want the other networks to cover it. Lastly, it means if you want to catch a good wrap-up you'll be forced to watch ABC. Unless, of course, the other networks just decide to defy ABC's ground rules in the name of "fair use"...

The event begins at 8pm EST and will be held at Philadelphia's National Constitution Center, less than a week before the Pennsylvania primary.

The last time Clinton and Obama met to debate was nearly two months ago.